The Spot-On range of diecast vehicles and accessories was produced by Tri-ang in Belfast, Northern Ireland between 1959 and 1967. Unlike their competitors, Spot-On models were to a constant scale of 1/42, a little larger than the Dinky and Corgi toys of that era. Another difference was that most of the models were available in several different colour schemes. Today Spot-On models are highly sought after by collectors.

Spot-On Models Ltd. was a new range from Tri-ang, a division of Lines Brothers, who, at one time, claimed to be the largest toy maker in the world. In the 1950s Dinky Toys, made in Liverpool, England, had a successful range of cars. These were joined in 1956 by Corgi Toys made by Mettoy. Corgi quickly grew to be the equal of Dinky in both the range and quality of its products. Not wishing to miss out on a commercial opportunity, Lines Bros. started its own range in 1959 using its factory in Northern Ireland. Murray Lines was put in personal charge of model selection.

The factory had been built in the Castlereagh area of Belfast just after World War II when Lines Bros were expanding (another factory in South Wales was opened at the same time). At various times, this factory produced several ranges of toys for various companies within the Lines Bros group, including Pedigree Soft Toys Ltd., Rovex Industries Ltd. and Lines Bros (Ireland) Ltd. In about 1960, a smaller factory was opened in the grounds of the Belfast factory specifically for the Spot-On range. There were three main product ranges: Spot-On cars, Spot-On dolls' house furniture, and Arkitex construction kits.

The objective of Spot-On was identical to that of Dinky and Corgi -to make true-to-life models that also served as toys. Consequently, these models needed to be detailed but robust. As Dinky and Corgi were already established, Spot-On required a marketing gimmick. Dinky and Corgi were both a little loose with their scale -typically around 1:48 for cars, but Spot-On decided always to be exactly, 'spot-on', 1:42. The company also adopted this scale for buses and commercial vehicles which made these models much larger than most Dinky and Corgi toys.

Spot-On tried first to establish itself in the British market, concentrating on a choice of cars that were familiar to Britons (the first was a UK Ford Zodiac). Even its name was one that was more easily understood in the UK than, for instance, in the States where Dinky and Corgi sold a large number of models. Spot-On models were well made, detailed and heavy. This, together with their larger size and smaller production numbers, made them more expensive than the competition. Consequently, they made a relatively small impact on the toy car market. However, backed by the Lines Brothers empire, the product range did not need to make an immediate profit to survive.

Although more conservative than Corgi Toys, Spot-On did introduce some innovations. In particular, several cars were redesigned to incorporate battery powered working headlights and, subsequently, detailed interiors which often featured interestingly dressed drivers and passengers.

Both large and small cars were chosen for inclusion in the range to fully accentuate the fixed 1:42 scale. Rolls Royce were represented initially by the Silver Wraith and, later, by the even larger Phantom V which featured working lights and members of the Royal Family as passengers. Smaller vehicles included the Isetta bubble car, the rare Meadows Frisky, the Fiat 500 and the Goggomobil. Also added were exotic sports cars such as the Aston Martin DB Mark III, Jensen 541, Daimler SP250, and Bristol 406, along with more mundane models such as the Hillman Minx and Austin A40.

In 1964, Lines Bros. acquired Meccano, the parent company of Dinky Toys and, rather than support two brands simultaneously, the owners decided to discontinue Spot-On in favour of Dinky. Some production continued in New Zealand and it was planned to produce, in Hong Kong, a range of American Cars for export to the United States but these were eventually re-labelled as the Dinky Toys '57' series -but retaining the 1:42 scale. From this point on Dinky adopted 1:42 as a general scale for its own new car and bus models although unlike Spot-On they did not always stick to this scale and continued to make both larger and smaller scales models to fit in with different price points in the market. Spot-On also made a line of doll's house furniture, using a different (1:16) scale.

Today, Spot-On models are as collectible as Dinky Toys and Corgi Toys and can command high prices. The Morris Minor 1000 is a particular favourite of collectors, because this car, which has almost cult status, was not in the Corgi and Dinky ranges. Unfortunately, many Spot-On models had artificial chrome attachments that have tended to not last as well as Dinky Toys of the era. However, there is a market in replacement parts, and some commercial enterprises will undertake full restoration of the models.